A very disinfected stethoscope

A couple of years ago I bought a Littmann 3200 electronic stethoscope. Love the thing. Fantastic (and adjustable) sound and recording capability and Bluetooth connection to upload those sounds to a companion app.

A couple of weeks back, the stethoscope started to glitch. Every now and then it would hard reset when I pressed the “-” button so I thought that was the end of it. I ordered a new one, planning on disassembling the old one once I had another good one. Today was that day.

Anyhow, as soon as I removed the membrane, it was pretty obvious what the problem was. Under the membrane, around the microphone, there was quite a collection of clear and sticky fluid. Looks a lot like the alcohol we use to disinfect hands and surfaces. I’m pretty sure the cleaning crew also cleans any stethoscopes they encounter and don’t think twice about dunking even electronic ones. I can’t imagine any other reason for fluid in my stethoscope.

Surprisingly, these stethoscopes are fairly easy to take apart, at least if you start at the right end, under the membrane. Sadly, the one part that can’t be removed is the keypad. So I never got to clean that out. But just by disassembling the scope and putting it back together, I seem to have fixed the problem.1

In the pictures, the blue one is the old, flaky one. The red (“burgundy”) is the new one. There’s a four year difference between them, but they have the exact same version of firmware.

Now I’ve got two… the blue one is the old one, the red… um… burgundy one is the new one.
Back side of microphone. Board, chip side.
Front of microphone and back of board. You can see some of the sticky fluid still on the microphone frame, though I did wipe most of it off before taking the picture.
After disconnecting the microphone and board.
Display part.
Empty shell. Almost. The keypad and its connector ribbon can’t be removed without major destruction.
The battery holder is pushed out the other way.
The LCD display module.
  1. I won’t leave it on my desk overnight anymore.

3 thoughts on “A very disinfected stethoscope”

  1. I purchased the Littmann 3200 with an engraving to have it returned to me (in appropriate language) but it faces the patient which I’d rather it not. I can’t seem to find a video or walk through on dissecting an electronic stethoscope (I’m nervous to break something). Did you pull the binaural pieces out of the tubing? Was it difficult, any tips? Thank you in advance!

  2. Tifany,

    I’m having a lot of fun imagining what that “appropriate language” could be.

    Anyway, the tubes themselves are just that, tubes with air in them. There is nothing electronic, since there is a speaker in the head itself. At least, that is how I understood the construction. So, if that’s true, you should be able to pull the tubes off and put them back on reversed. On the other hand, the proximal pieces go over the metal tubes with the earpieces, and to me it looks like they’ve been crimped on, probably with a heat gun or something. I think you need to find out how the metal pieces are joined together before attempting anything. Maybe take an x-ray of it first?

    It does seem like a difficult operation, though. Personally, I wouldn’t risk it. Maybe better find a way to change, cover or remove the engraving? (I don’t even know how it looks, not having had any engraved myself.)

  3. Hello, I have the same problem; but I work alone…noone can put any liquid on it.
    I found my scope not working anymore. I thought it was the battery but after replacing it doesn’t work anyway.
    So I’m planning to disassembly and understand what’s going on.
    Thank you for sharing pictures

Leave a Reply

Your email address will not be published. Required fields are marked *